Pre-heat the oven to 180ºC and line a baking tray with greaseproof paper
Sprinkle a third of the grated parmesan cheese on the lined baking tray. Place the potato slices onto the cheesed baking tray in lines, making sure each slice overlaps with the previous one, and that the next layer overlaps with the previous
Once the potatoes have been layered up, sprinkle over another third of the grated parmesan and cook in the oven for 10 minutes
Meanwhile, cook the meat filling. Spray a frying pan with some low calorie cooking spray and fry the onion, garlic and oregano until softened. This will take around 5 minutes
Add the minced beef to the frying pan and lightly brown before adding the tomato puree, beef stock cube and water. Gently simmer, stirring frequently. The mixture should not have too much liquid
When the potatoes have been baking for 10 minutes, take them out of the oven, cover with some greaseproof paper and place another baking tray on top. Weigh the top tray down with a heavy baking tray or oven proof casserole lid. Place back into the oven for 20 minutes
Once the potatoes are cooked, remove the weighted baking tray. Spread the mince over the potatoes, covering the whole surface. Carefully roll the potatoes and mince up like a swiss roll, using the short side to roll. Push back any potato slices that might've escaped!
Sprinkle over the remaining parmesan and pop back in the oven for 15 minutes until golden and bubbly
Serve with your choice of accompaniment